Ophthalmic lenses and compositions and methods for producing same

ABSTRACT

Ophthalmic lenses, such as corneal contact lenses, include a lens body made of a composition including a lens body made of a composition including a first crosslinked polymer material which is water swellable, and a second polymeric material, other than the first material, selected from water soluble polymeric materials, water swellable polymeric materials and mixtures thereof. The second material is physically immobilized by the first material. Such lenses provide increased water retention and/or increased water content and/or increased modulus and/or reduced friction which increases lens wearer comfort. Compositions and methods for providing such lenses and compositions are also provided.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to ophthalmic lenses, compositionsuseful for inclusion in such lenses, and methods for producing suchlenses and compositions. More particularly, the invention relates topolymeric ophthalmic lenses, such as corneal contact lenses and thelike, polymeric compositions useful included in ophthalmic lenses andmethods for producing such lenses and compositions.

[0002] Hydrophilic lenses, such as corneal contact lenses, are oftenformed from covalently cross-linked polymers based on hydrophilicderivatives of acrylic or methacrylic acid, hydrophilic vinylic monomerssuch as vinylpyrrolidone, and the like. When hydrated, these hydrophiliccross-linked polymers can be referred to as hydrogels and includerelatively large quantities of water without dissolving. Such polymersmay include minor amounts of polymeric units derived from lesshydrophilic, or even hydrophobic, monomers to confer mechanical strengthand other useful properties.

[0003] Although conventional hydrophilic polymer or hydrogel lenses areuseful and effective, some problems do present themselves, from time totime. For example, conventional hydrophilic contact lenses, particularlyafter long periods of in-the-eye use, do have a tendency to lose watercontent. Reduction in water content tends to detrimentally affect thephysical structure and/or optical properties of the lens. This reductionin water content can lead to lens wearer discomfort and even to actualirritation or other damage to the eye. In addition, such conventionallenses may lose lubricity or exhibit relatively large amounts offriction with the corneal surface, which also can cause lens wearerdiscomfort and/or eye irritation and the like. Such reduced lens watercontent and/or reduced lubricity can result in the lens wearerperceiving that his/her eye is dry. Such “dry eye” phenomenon can beovercome through the use of eye drops and/or lubricants. However, itwould be advantageous to reduce or even substantially eliminate theseproblems without the need for eye drops or separate lubricants.

[0004] In short, there is a continued need for enhanced ophthalmiclenses, e.g., corneal contact lenses, enhanced materials of constructionfor such lenses and enhanced methods for producing such lenses andmaterials.

SUMMARY OF THE INVENTION

[0005] New ophthalmic lenses, such as corneal contact lenses, polymericcompositions useful for inclusion in such ophthalmic lenses, and methodsfor producing such lenses and polymeric compositions have beendiscovered. The present invention provides substantial benefits in termsof reducing discomfort and/or irritation to the wearer of the presentlenses as a result of wearing such lenses, for example, relative towearing a conventional lens. The present lenses, which include thepresent compositions, preferably provide for increased water contentand/or increased water retention and/or reduced surface evaporation ofwater. The present contact lenses exhibit reduced friction towardhydrophilic surfaces such as the cornea. Further, such lenses haveeffective, and even enhanced, modulus, and structural and opticalstability, for example, relative to conventional lenses. A lens wearercan often wear the present lenses effectively for relatively longerperiods of time and/or with reduced or no harmful effects relative toconventional lenses.

[0006] The present methods for producing polymeric compositions andlenses are relatively straightforward to practice and providecompositions and lenses which have controlled characteristics useful inproducing substantial benefits, for example, one or more the benefits ofthe present lenses described herein.

[0007] In one broad aspect, the present invention is directed toophthalmic lenses comprising lens bodies. Such lens bodies comprisecompositions including a first polymer material, preferably a firstcross-linked polymer material, which is water swellable; and a secondpolymeric material, other than the first material, selected from watersoluble polymeric materials, water swellable polymeric materials andmixtures thereof. The second material is immobilized, preferablyphysically immobilized, by the first material. In one embodiment, forexample, with the second material being a water soluble material, thecomposition included in the present lenses preferably may be considereda pseudo-interpenetrating network. With the second material selectedfrom water swellable materials, the composition in the lenses preferablymay be considered a true interpenetrating network of the first materialand the second material.

[0008] Without wishing to limit the invention to any particular theoryof operation, it is believed that such structures of the combinations offirst materials and second materials in accordance with the presentinvention provide the effective and surprising properties and benefitsto the present lenses.

[0009] The first material and the second material are chosen or selectedto provide one or more desired properties, for example, lenses with oneor more desired properties which provide one or more benefits to thelenses and/or the lens wearers.

[0010] Advantageously, the lens bodies in accordance with the presentinvention, when hydrated, exhibit one or more of the followingbeneficial characteristics or properties:

[0011] increased water retention relative to a substantially identicallens body without the second material;

[0012] increased equilibrium water content relative to a substantiallyidentical lens body without the second material;

[0013] reduced surface evaporation of water relative to a substantiallyidentical lens body without the second material;

[0014] increased modulus or tensile strength relative to a substantiallyidentical lens body without the second material; and

[0015] a reduced coefficient of friction relative to a substantiallyidentical lens body without the second material.

[0016] Lenses, such as contact lenses, which include and/or retainincreased amounts of water are effective in providing increased lenswearer comfort and/or reducing the risk of irritation and/or otherdamage to the eye of the lens wearer. Reducing the friction between thelens and the eye, for example, the cornea of the eye, such as bymaintaining an increasing water content and/or reducing coefficient offriction, also increases comfort and reduces risk of irritation. Lenseswith increased modulus or tensile strength have longer useful livesand/or can be made more thin to enhance lens wearer comfort. Inaddition, lenses with such reduced coefficients of friction are able tobe worn without the lens wearer perceiving excessive eye dryness. Thepresent lenses often have what may be termed a slippery or lubriciousfeel, for example, because of the increased water content and/or thereduced coefficient of friction. In addition, by selecting suitablemonomers from which the first material and the second material are made,the present lenses can advantageously have a reduced tendency toaccumulate proteinaceous and other deposit material.

[0017] In another broad aspect of the present invention, methods forproducing ophthalmic lenses. In general, such methods comprise:

[0018] providing a lens body comprising a lens composition including afirst polymer material, preferably a first crosslinked polymer material,which is water swellable;

[0019] introducing a monomeric component into the lens body, themonomeric component preferably being soluble in at least one memberselected from the group consisting of water, water miscible solvents andmixtures thereof; and

[0020] subjecting the monomeric component in the lens body to effectiveconditions, for example, effective polymerization conditions, to form asecond polymeric material selected from water soluble polymericmaterials, water swellable polymeric materials and mixtures thereof. Thesecond material is immobilized, preferably physically immobilized, bythe first material.

[0021] In one embodiment, the monomeric component is substantially freeof a cross-linker. Alternately, the monomeric component may include aneffective amount of a cross-linker.

[0022] In addition, the monomeric component may include an amount of apolyfunctional monomer, for example, a di-functional monomer, effectiveto increase the molecular weight, such as by increasing the chainlength, of the second material relative to a similar polymeric material,for example, produced without the polyfunctional monomer. In thisembodiment, the polyfunctional monomer preferably is employed inembodiments with the resulting or final second material is to be watersoluble.

[0023] Each and every feature described herein, and each and everycombination of two or more of such features, is included within thescope of the present invention provided that the features included insuch a combination are not mutually inconsistent.

DETAILED DESCRIPTION

[0024] The present ophthalmic lenses may be of any suitable form, forexample, adapted to be placed on or in a mammalian or human eye. Thus,the present lenses can be corneal contact lenses, corneal onlays,corneal inlays, intraocular lenses and the like. However, the presentinvention is particularly useful with regard to corneal contact lensesor simply contact lenses, which are adapted to be repeatedly placed onand removed from the surface of the cornea. Although the descriptionherein emphasizes contact lenses, it is to be understood that theinvention is not limited thereto.

[0025] The lens bodies of the present ophthalmic lenses comprise a firstpolymer material, preferably a first cross-linked polymer material,which is water swellable; and a second polymeric material, other thanthe first material, selected from water soluble polymeric materials,water swellable polymeric materials and mixtures thereof. The secondmaterial is immobilized, preferably physically immobilized, by the firstmaterial. Preferably, the second material is substantially notcovalently bonded to the first material.

[0026] Preferably, the lens bodies of the present ophthalmic lensesexhibit at least one of increased water retention, increased equilibriumwater content, reduced surface evaporation of water, increased modulusor tensile strength and a reduced coefficient of friction relative to asubstantially identical lens body without the second material. Asdiscussed in more detail elsewhere herein, each of these features, aloneor in any combination, is effective to provide properties to the presentlenses which are of substantial benefit to the lenses themselves and/orto the wearers of the lenses.

[0027] In one useful embodiment, the second material is substantiallyuncross-linked. Alternately, the second material may be cross-linked. Inone embodiment, the second material preferably comprises homopolymers,although copolymers including units of two or more monomers may beemployed.

[0028] The first material is present in the present lens bodies orcompositions in an amount effective to hold or immobilize, for example,physically hold or immobilize, the second material, in particular whenthe lens bodies or compositions are hydrated at equilibrium conditions.Such first material preferably is present in an amount in a range ofabout 10% to about 99.9% by weight, more preferably about 60% to about99.9% by weight, based on the water-free weight of the ophthalmic lensor of the composition comprising the first material and the secondmaterial. The second material is present in the present lens orcomposition, for example, in an amount effective to provide at least onebenefit, e.g., as described elsewhere herein, to the lens orcomposition. The second material preferably is present in an amount in arange of about 0.1% to about 90% by weight, more preferably about 0.1%to about 40% by weight, based on the water-free weight of the ophthalmiclens or composition comprising the first material and the secondmaterial.

[0029] In a very useful embodiment, the first material is selected fromhydrogel-forming polymers and mixtures thereof. For example, the firstmaterial may include units, that is polymer units derived from monomersused to produce the first material, derived from at least hydrophilicmonomeric component, for example, an at least one hydrophilicethylenically unsaturated monomer. The first material preferably ispresent as a hydrogel in the presence of an effective amount of water toswell the first material.

[0030] The first material more preferably includes units derived fromone or more members selected from hydroxyalkyl acrylates, hydroxyalkylmethacrylates, N-vinylpyrrolidone, acrylamides, vinyl alcohol,hydrophilic polyurethane precursors, acrylates, methacrylates,substituted counterparts thereof and mixtures thereof.

[0031] As used herein, the term “substituted counterparts thereof”refers to entities, e.g., compounds, which include one or moresubstituents and are effective to function in the present inventionsubstantially like the unsubstituted entities, for example, thecompounds listed herein.

[0032] Conventional cross-linking monomeric components may be employedin amounts effective to produce the desired degree of cross-linking ofthe first material.

[0033] The first material may be selected from materials which are wellknown and conventionally used in producing hydrophilic or soft contactlenses. For example, the first material may be produced from a mixtureof monomers including methacrylic acid, 2-hydroxyethyl methacrylate(HEMA), and ethyleneglycol dimethacrylate cross-linking monomer togetherwith a polymerization initiator, such as a thermal initiator. Suchmixture can be placed in molds having lens shaped, for example, contactlens shaped, cavities and subjected to elevated temperature, forexample, in a range of about 60° C. to about 120° C., to effectthermopolymerization of the monomer mixture and form lens blanks, forexample, contact lens blanks. Preparation of lens blanks by UV radiationin the presence of a photoinitiator such as diethoxyacetophenone,1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone,phenothiazine, diisopropylxanthogen disulfide, benzoin, benzoin methylether, other benzoin derivatives, 2,2′-azo-bis-isobutyro-nitrile and thelike and mixtures thereof is also a useful method.

[0034] The first material may be cationic, anionic, nonionic or amaterial having a substantially balanced cationic/anionic charge, forexample, formed from a composition comprising a cationic-anionic pair ofmonomers and hydrophilic and/or hydrophobic monomers. See Sulc et alU.S. Pat. No. 5,270,415, the disclosure of which is incorporated in itsentirety herein by reference.

[0035] One advantage of ophthalmic lenses including a first material,and preferably a second material as well, having a substantiallybalanced cationic/anionic charge is that such lenses have asignificantly reduced tendency to accumulate proteinaceous materials,cell fragments, and other soilants or deposit materials on the surfacesof the lenses. This highly advantageous property is relative to lensesmanufactured from hydrogels having a significant or substantial cationicor anionic surface charge. Moreover, such reduced deposit accumulationtendency is in addition to the other benefit or benefits, as describedherein, of the present invention.

[0036] Suitable anionic monomeric components useful in producing thefirst material include, but are not limited to, carboxylic acids such asacrylic acid, methacrylic acid, itaconic acid, maleic acid,2-vinylpropionic acid, 4-vinylpropionic acid and the like and mixturesthereof; and sulfonic acids such as methacryloyloxypropyl-sulfonic acid,vinylsulfonic acid, p-styrenesulfonic acid and the like and mixturesthereof. Suitable cationic monomeric components include, but are notlimited to, primary, secondary and tertiary amines such asaminoethylmethacrylate, methylaminoethylmethacrylate,N,N-dimethylaminoethylmethacrylate, N,N-diethanolaminoethylmethacrylate,N,N-dimethoxyethylamino-ethylmethacrylate, vinyl amine, aminostyrene,2-vinyl pyridine, 4-vinyl pyridine, morpholinomethacrylate,N-(2-vinyloxyethyl) piperidine and the like and mixtures thereof; andquaternary ammonium compounds such as 2-trimethylammoniumethylmethacrylic hydroxide, 2-trimethylammoniumacrylic hydroxide,2-trimethylammoniumethyl methacrylic chloride,2-trimethylammoniummethylacrylic chloride,2-methacryloyloxyethyltrimethylammonium methyl sulfate, 2 hydroxy-3methacryloxyloxypropyltrimethylammonium chloride, and the like andmixtures thereof. Cationic-anionic monomeric component pairs include,but are not limited to, N-(3-sulfopropyl)-methacroyloxyethyl-N,—N-dimethylammonium-betain (SPE),N-(3-sulfopropyl)-N-methacrylamidopropyl-N,N-dimethylammonium-betain(SPP), 1-(3-sulfopropyl)-2-vinyl-pyridinium-betain (SPV),N-methacryloyloxyethyl-N, 2-ethylcarboxybetain,N-(3-carboxypropyl)-N-methylaminoethylmethacrylate,N-(3-carboxypropyl)-N-methylaminomethacryloyloxyethyl-dimethylammonium-betain(CPE), N-(3-carboxypropyl) aminoethylmethacrylate,2-(methacryloyloxy)ethyl-2-(trimethylammonium) ethylphosphate, and thelike and mixtures thereof.

[0037] A monomer mixture is formed of a nonionic monomeric component, acharged monomeric component or a cationic-anionic monomeric componentpair with at least one hydrophilic monomeric component, such as at leastone ethylenically unsaturated hydrophilic monomeric component,including, but not limited to, 2-hydroxyethyl methacrylate (HEMA),hydroxypropylmethacrylate, vinylpyrrolidone, glycerylmethacrylate,acrylamide, and the like and mixtures thereof.

[0038] A cross-linking monomeric component preferably is also includedin the monomer mixture. Examples of useful cross-linking monomericcomponent agents or components include, but are not limited to, ethyleneglycol dimethacrylate (EGDMA) and diacrylate, diethyleneglycoldimethacrylate and diacrylate, 1,3-propanediol dimethacrylate anddiacrylate, 2,2-dimethylpropanediol diacrylate, tripropylene glycoldimethacrylate and diacrylate, 1,3-butylene glycol dimethacrylate anddiacrylate, divinylbenzene, sorbitol dimethacrylate, bis-acrylamide, andthe like and mixtures thereof.

[0039] Polymerization of the monomer mixture is carried out usingconventional techniques which are well known in the art. The firstmaterial can be formed into a lens blank using conventional techniques,such as molding, spin casting and the like. Since such techniques arewell known to those of ordinary skill in the art, a detailed descriptionthereof is not presented here.

[0040] The second material is other than the first material and isimmobilized by the first material. The second material may be watersoluble, for example, substantially uncross-linked; or may be waterswellable, for example, a cross-linked polymeric material. Combinationsof water soluble polymeric materials and water swellable polymericmaterials are also useful as the second materials and are includedwithin the scope of the present invention. The second materialpreferably is substantially not covalently bonded to the first material.The second material may include units derived from at least onehydrophilic monomer component, for example, at least one ethylenicallyunsaturated hydrophilic monomeric component. The monomeric componentsfrom which the second materials are derived, for example, the at leastare ethylenically unsaturated monomeric component, preferably aresoluble in at least one member selected from water, water misiblesolvents and mixtures thereof. Such solubility is particularly useful inproducing the present second materials by solution polymerization, whichis a preferred production technique, for example, as demonstrated in theExamples set forth hereinbelow.

[0041] In one embodiment, the monomeric components from which the secondmaterials are derived, for example, the at least one ethylenicallyunsaturated hydrophilic monomeric component, are polymerizable to formlinear or branched chain water soluble polymers or copolymers. Suchwater soluble polymer or copolymers are believed to be physicallyimmobilized by the first polymer material by physical entanglements ofthe polymers or copolymers in the first material in what might beconsidered or termed a pseudo-interpenetrating network. Alternately, themonomeric components from which the second materials are derived, forexample, the at least one ethylenically unsaturated hydrophilicmonomeric component, are polymerizable, and cross-linkable, to formpolymers or copolymers which are water swellable, and not water soluble.Such cross-linked, water swellable polymers or copolymers are believedto be physically immobilized by the first material in a trueinterpenetrating network. In any event, after hydration of the presentcompositions or lens bodies the polymers or copolymers of the secondmaterials are held or immobilized by the first materials.

[0042] Hydrophillic monomeric components suitable for production of thepolymers and copolymers immobilized within the first materials include,but are not limited to, hydrophillic vinylic monomers, such as vinyl(C₄-C₄₅)alkyl ethers, vinyl (C₇-C₄₉) alkenoic acids and the like andmixtures thereof; hydroxy substituted (C₅-C₄₅) alkyl, alkoxy-alkyl andpolyalkoxy-alkyl and mono- or bi-cycloaliphatic fumarates, maleates,acrylates, methacrylates, acrylamides and methacrylamides, and the likeand mixtures thereof; acrylic acid, methacrylic acid, the correspondingamino or mono- and di-(lower alkyl) amino substituted acrylic monomersand the like and mixtures thereof; and vinyl-lactams and the like andmixtures thereof. Typical monomers include, but are not limited to,2-hydroxyethyl, 2-hydroxypropyl, and 3-hydroxypropyl acrylates andmethacrylates; N-vinylpyrrolidone; N,N-dimethylaminoethyl methacrylate;methoxyethyl-, ethoxyethyl, methoxy-ethoxyethyl and ethoxy-ethoxyethylacrylates and methacrylates; (meth)acrylamides like N,N-dimethyl,N,N-diethyl, 2-hydroxyethyl-, 2-hydroxypropyl-, and 3-hydroxypropylacrylamides and methacrylamides; vinyl sulfonic acid; styrene sulfonicacid; 2-methacrylamide-2-methyl propane-sulfonic acid and the like andmixtures thereof. Many, if not all, of the hydrophilic monomers usefulto produce the present first materials are also useful to produce thesecond materials, and vice versa.

[0043] In one embodiment, the second material preferably includes unitsderived from one or more of acrylic acid, hydrophilic derivatives ofacrylic acid, methacrylic acid, hydrophilic derivatives of methacrylicacid, cationic/anionic pairs of monomeric components, cationic monomericcomponents, anionic monomeric components, nonionic monomeric components,hydrophilic vinylic monomeric components, salts thereof and mixturesthereof.

[0044] In the event the second material is to be water swellable, across-linking monomeric component is included in an amount effective toform a cross-linked second material which is water swellable.

[0045] Useful or suitable cross-linking monomeric components forinclusion in the monomers used to produce water swellable secondmaterials may be selected from among such cross-linkers as areconventionally used, for example, in soft contact lens production.Examples of useful cross-linking monomeric components are set forthelsewhere herein.

[0046] Even if the second material is to be water soluble, rather thanwater swellable, it may be advantageous to increase the molecular weightof the second material to facilitate effective immobilization of thesecond material by the first material. In this circumstance, a chainextending, e.g., di-functional and/or tri-functional, monomericcomponent preferably is included in the monomers used to form the secondmaterial in an amount effective to increase the molecular weight of thismaterial, as desired or to the desired extent.

[0047] Monomeric components suitable for modifying or increasing themolecular weight of the polymers or copolymers immobilized within thefirst materials include, but are not limited to, polyvinyl-, typicallydi- or tri-vinyl-monomers, such as di- or tri-acrylates andmethacrylates; dihydric or higher hydric alcohol acrylates andmethacrylates, such as ethyleneglycol-, triethylene glycol-,tetraethylene glycol-, propylene glycol-, butylene glycol-,hexane-1,6-diol-thio-diethylene glycol- and neopentyl glycol-diacrylatesand dimethacrylates, neopentyl glycol diacrylate; trimethylolpropanetriacrylate and trimethacrylate and the like;N,N-dihydroxyethylene-bisacrylamide and -bismethacrylamide; diallylcompounds such as diallylphthalate and triallyl cyanurate;divinylbenzene; ethylene glycol divinyl ether; and the like and mixturesthereof. Preferred such monomeric components include ethylene glycoldimethacrylate, diethylene glycol dimethacrylate, 1,4-butane dioldi(meth)acrylate, neopentyl glycol diacrylate and the like and mixturesthereof.

[0048] The polymers or copolymers immobilized within the first materialpreferably are prepared by free-radical polymerization in solution andusing heat-, redox- or UV-activated initiators.

[0049] Typical heat activated initiators include, but are not limitedto, peroxides or azo catalysts having a half-life at the polymerizationtemperature of at least 20 minutes. Useful peroxy compounds include, butare not limited to, isopropyl percarbonate, tert-butyl peroctoate,benzoyl peroxide, lauroyl peroxide, decanoyl peroxide, acetyl peroxide,succinic acid peroxide, methyl ethyl ketone peroxide, tert-butylperoxyacetate, propionyl peroxide, 2,4-dichlorobenzoyl peroxide,tert-butyl peroxypivalate, pelargonyl peroxide, 2,5-dimethyl-2,5-bis(2-ethylhexanoyl-peroxy)hexane, p-chlorobenzoyl peroxide,tert-butyl peroxybutyrate, tert-butyl peroxymaleic acid,tert-butyl-peroxyisopropyl carbonate, bis(1-hydroxycyclohexyl)peroxideand the like and mixtures thereof. Useful azo compounds include, but arenot limited to, 2,2′-azo-bis-isobutyro-nitrile,2,2′-azo-bis(2,4-dimethylvaleronitrile), 1,1′-azo-bis (cyclohexanecarbonitrile), 2,2′azo-bis(2,4-dimethyl-4-methoxyvaleronitrile) and thelike and mixtures thereof.

[0050] Typical redox initiators include, but are not limited to,ammonium persulfate-sodium thiosulfate, potassium sulfate-Mohr's salt,and one or more peroxides with reducing agents such as sodiumthiosulfate. Hydroxylamine hydrochloride, hydrazine hydrate, ascorbicacid, oxalic acid and citric acid are also suitable reducing agents foruse in combination with oxidizing agents.

[0051] Typical UV (ultraviolet light)-activated initiators include, butare limited to, the photoinitiaters previously identified.

[0052] Other free radical generating mechanisms can be employed, such asX-rays, electron-beams and UV-radiation.

[0053] Methods for producing ophthalmic lenses or compositions, asdescribed herein, include:

[0054] providing a lens body comprising a lens composition including afirst polymer material, preferably a first cross-linked polymermaterial, which is water swellable, or providing a first polymermaterial, preferably a first cross-linked polymer material, which iswater swellable. A monomeric component, preferably including apolymerization initiator component, as described elsewhere herein, isintroduced into the lens body or the first material. The monomericcomponent preferably is soluble in at least one member selected fromwater, water miscible solvents and mixtures thereof. The monomericcomponent preferably is introduced into the lens body or the firstmaterial as a solution, for example, in water and/or water misciblesolvents. The monomeric component in the lens body or the first materialis exposed or subjected to effective conditions, that is effectivepolymerization conditions, to form a second polymeric material selectedfrom water soluble polymeric materials, water swellable polymericmaterials and mixtures thereof. The second material formed isimmobilized, preferably physically immobilized, by the first material,for example, as described elsewhere herein.

[0055] The lens bodies, first materials and monomeric components usefulto produce the second materials in accordance with the present methodsare substantially as described elsewhere herein.

[0056] The conditions at which the second material is formed areselected so as to form the desired material. Such conditions may varydepending on the first material and monomeric component being employed,on the type (e.g. water soluble or water swellable) of second materialdesired, on the type of polymerization initiator used and on the likefactors. Such conditions preferably are selected so that the firstmaterial is not substantially detrimentally affected.

[0057] Typical conditions include, but are not limited to, temperaturesin a range of about 10° C. to about 100° C., preferably about 30° C. toabout 80° C., polymerization times in a range of about 1 minute to about48 hours, preferably about 5 minutes to about 45 minutes. Preferably,the polymerization occurs in an aqueous solution.

[0058] After the second material is formed, the lens body or thecomposition is preferably washed, with water and the like, to remove anyunreacted monomeric component.

[0059] In one useful embodiment, the second material formed issubstantially non-hydrophilic. In this instance, the formed secondmaterial preferably is converted, for example, by salt formation, into ahydrophilic second material. To illustrate, the formed material may bepolymethacrylic acid which is exposed to alkali metal acid salt to formthe corresponding alkali metal salt of polymethacrylic acid, a watersoluble, hydrophilic material.

[0060] Compositions, for example, in forms other than ophthalmic lenses,which comprise a water swellable, first polymer material, preferably afirst cross-linked polymer material, and a second material, other thanthe first material and polyacrylic acid, selected from water solublepolymeric materials, water swellable polymeric materials and mixturesthereof immobilized preferably physically immobilized by the firstmaterial are also included within the scope of the present invention.Such compositions, for example, such compositions which are hydrated,such as those compositions with substantially equilibrium watercontents, are useful for various applications in the biomedical andpharmaceutical fields, such as in implant materials, catheters, drugdelivery devices, etc. Such compositions preferably are effective oruseful in the ophthalmic lenses of the present invention.

[0061] The following non-limiting Examples illustrate certain aspectsand advantages of the present invention.

EXAMPLE 1

[0062] A series of contact lenses were cast in polypropylene molds bythermopolymerization of a monomer mixture including methacrylic acid,ethyleneglycol dimethacrylate, a thermal initiator and 2-hydroxyethylmethacrylate. The resulting lenses, which had a composition similar toOcufilicon D, were utilized for further experiments.

EXAMPLE 2

[0063] Each of four contact lenses prepared according to Example 1 wasimmersed in 2 ml of an aqueous solution including 1% w/v NaCl and 0.1,0.2, 0.4, and 0.6% w/v, respectively, of methacrylic acid in a 5 mlglass vial. The solution and lens in each of the vials were purged withoxygen free nitrogen for 1 minute, and then the vials were sealed. Thevials were then placed in a 50° C. water bath and left to equilibratefor 15 minutes. Then 40 microliters of 5% w/v V-50[2,2′-azobis(amidinopropane) dihydrochloride] initiator was injectedthrough the septum in each vial using a Hamilton microsyringe. The vialswere maintained in the 50° C. water bath for 30 minutes to effectpolymerization of the methacrylic acid and then the polymerization wasstopped by dropping the vials in an icy water bath.

[0064] The vials were opened and the lenses placed in extraction basketsin 1 w/v of NaHCO₃ solution for 30 minutes at 50° C. to transform thepolymethacrylic acid produced during the polymerization in a sodium saltof polymethacrylic acid. The lenses were equilibrated in phosphatebuffered saline at pH 7.2, autoclaved for 20 minutes at 120° C. andtheir water contents were determined.

[0065] Results of certain tests on the untreated lens and the treatedlenses were as follows: Untreated Lens 0.1% MAA 0.2% MAA 0.4% MAA 0.6%MAA Water content,   50.9%   54.2%   56.9%   59.0%   61.0% by wt. Dryweight gain    0.0%    3.0%    3.5%    5.0%    6.5% Base Curve [mm] 8.40  8.60  8.80  8.90  8.95 Diameter [mm] 13.70 14.10 14.86 15.0015.70

[0066] The above-noted treatments resulted in highly slippery contactlenses with increased water contents, for example, relative to the watercontents of the untreated contact lenses. Water contents of the lensesbefore and after autoclaving and 60 minutes of boiling remainedsubstantially the same indicating that a linear polymer of sodiumpolymethacrylic acid salt was permanently entrapped in the structures ofthe lenses.

EXAMPLE 3

[0067] Following the procedure described in Example 2, two contactlenses, made of crosslinked copolymer of hydroxyethyl methacrylate andmethyl acrylate crosslinked with ethyleneglycol dimethacrylate (EGDMA)were treated with 0.1% w/v methacrylic acid solution and furtherevaluated for any change in mechanical characteristics. Both modulus andtensile strength of the treated lenses were about 30% greater than theuntreated lenses.

EXAMPLE 4

[0068] Two lenses prepared according to Example 1 were each immersed in2 ml of an aqueous solution containing 1% w/v of NaCl, and 3% w/v ofsodium salt of sulfopropyl methacrylate (SPM) or 3% (w/v)N-(3-sulfopropyl)-methacroyloxyethyl-N,N-dimethyl ammonium-betain (SPE).The lenses were treated and processed the same way as described inExample 2 except that no NaHCO₃ was used. The treatments resulted inhighly slippery lenses with permanently entrapped linear polymers of SPMand SPE.

EXAMPLE 5

[0069] Two lenses prepared according to Example 1 were each immersed in2 ml of a deionized water solution of 5% w/v of diethyleneglycolmethacrylate (DEGMA) or 5% (w/v) glycerol methacrylate (GMA). The lenseswere treated and processed in the same way as described in Example 4.The treatments resulted in slippery lenses with permanently entrappedlinear polymers of DEGMA and GMA.

EXAMPLE 6

[0070] Three lenses, designated Lens (A), Lens (B) and Lens (C),prepared according to Example 1, were each immersed in 2 ml of adeionized water solution of 5% w/v of diethyleneglycol methacrylate(DEGMA), and the lenses were treated and processed the same way asdescribed in Example 4, except that modified polymerization conditionswere employed as follows: Lens (A) 40 microliters of 5% (w/v) V-50initiator was injected through the vial's septum using a Hamiltonmicrosyringe and polymerization was carried out for 30 minutes at 50°C.; Lens (B) 20 microliters of 5% w/v V-50 initiator was injectedthrough the vial's septum and polymerization was carried out for 2 hoursat 50° C.; and Lens (C) 20 microliters of 5% w/v V-50 initiator wasinjected through the vial's septum and polymerization was carried outfor 4 hours at 45° C.

[0071] Results of certain tests on the untreated lens and the treatedlenses were as follows: Untreated lens A B C water Content, 50.9% 54.5%55.8% 56.0% by wt. Dry weight gain  0.0%   40%   50%   65% Diameter (mm)13.7 15.9 18.0 18.5

[0072] All three treatments resulted in highly slippery lenses withsignificantly enlarged dimensions while the water content increasedmoderately relative to the untreated lens.

EXAMPLE 7

[0073] A series of contact lenses were cast in polypropylene molds bythermopolymerization of a monomer mixture including ethyleneglycoldimethacrylate, a thermal initiator and 2-hydroxyethyl methacrylate. Theresulting lenses, which had a composition similar to Polymacon, wereutilized for further experiments.

EXAMPLE 8

[0074] Three lenses prepared according to Example 7 were each immersedin 2 ml of a deionized water solution containing 0.5, 1.0, and 5.0% w/v,respectively, of methacrylic acid, in a 5 ml glass vial. Then 3microliters of 10% w/v V-50 initiator was added to each of the vials.The solutions with the lenses were purged with oxygen-free nitrogen for1 minute, and then the vials were sealed. The vials were then placed ina 40° C. water bath for 16 hours. The vials were opened and the lenseswere placed in extraction baskets in 1% w/v of NaHCO₃ solution for 30minutes at 50° C. The lenses were then equilibrated in phosphatebuffered saline at pH 7.2, autoclaved 20 minutes at 120° C. and theirwater contents were determined.

[0075] Results of certain tests on the untreated lens and the treatedlenses were as follows: Untreated lens 0.5% MAA 1.0% MAA 5.0% MAA WaterContent, 37.6% 42.5% 45.6% 58.1% by wt. Dry Weight  0.0%  1.1%  1.4% 6.1% Gain

[0076] The above-noted treatments resulted in slippery contact lenseswith increased water contents. Water contents of the lenses before andafter autoclaving and 60 minutes of boiling in saline solution remainedsubstantially the same, indicating that a linear polymer of sodiumpolymethacrylic acid salt was permanently entrapped in the structures ofthe lenses.

EXAMPLE 9

[0077] Three lenses prepared according to Example 7 were each immersedin 2 ml of a deionized water solution including 0.5, 1.0, and 5.0% w/v,respectively, of methacrylic acid, sodium salt in 5 ml glass vials. Then3 microliters of 10% w/v V-50 initiator was injected into each of thevials. The solutions and the lenses were purged with oxygen-freenitrogen for 1 minute and the vials were sealed. The vials were thenplaced in a 400 water bath for 16 hours. Finally, the lenses wereequilibrated in phosphate buffered saline at a pH of 7.2, autoclaved 20minutes at 120° C. and their water contents were determined.

[0078] Results of certain tests on the untreated lens and the treatedlenses were as follows: Untreated 0.5% MAA, 1.0% MAA, 50% MAA, lens Na⁺Na⁺ Na⁺ Water Content, 37.6% 38.6% 39.1% 53.1% by wt. Dry weight  0.0% 1.0%  1.1%  5.6% gain

[0079] The above-noted treatments resulted in slippery contact lenseswith increased water contents. Water contents of the lenses before andafter autoclaving and 60 minutes of boiling in saline solution remainedsubstantially the same, indicating that the linear polymer of sodiumpolymethacrylic acid salt was permanently entrapped in the structure ofthe treated lens.

EXAMPLE 10

[0080] Three lenses prepared according to Example 7 were each immersedin 2 ml of a deionized water solution of 0.5, 1.0, and 5.0% w/v,respectively, of N-vinylpyrrolidone in 5 ml glass vials. Then 3microliters of 10% w/v V-50 initiator was injected into each of thevials. The solutions with the lenses were purged with oxygen-freenitrogen for 1 minute and the vials were sealed. The vials were thenplaced in a 40° C. water bath for 16 hours. The lenses were thenequilibrated in phosphate buffered saline at a pH of 7.2, autoclaved 20minutes at 120° C. and their water contents were determined.

[0081] Results of certain tests on the untreated lens and the treatedlenses were as follows: Untreated lens 0.5% NVP 1.0% NVP 5.0% NVP Watercontent, 37.6% 35.2% 38.4% 39.0% by wt. Dry weight 0.0% 1.3% 1.5% 1.6%content

[0082] The above-noted treatments resulted in slightly slippery contactlenses with increased water content. Water content of the lenses beforeand after autoclaving and 60 minutes of boiling in saline solutionremained substantially the same indicating that the linear polymer ofN-vinylpyrrolidone is permanently entrapped in the structure of thetreated lenses.

EXAMPLE 11

[0083] Three lenses prepared according to Example 7 were each immersedin 2 ml of a deionized water solution of 0.45% w/v of SPE+0.05% w/v ofHEMA, 0.9% w/v of SPE+0.1% w/v of HEMA, and 4.5% w/v of SPE+0.5% w/v ofHEMA in 5 ml glass vials. The lenses were further treated as describedin Example 10.

[0084] Results of certain tests on the untreated lens and the treatedlenses were as follows: Un- 0.45 + 0.05% 0.9 + 0.1% 4.5 + 0.5% treatedSPE + SPE + SPE + lens HEMA HEMA HEMA Water content, 37.6% 42.5% 45.0%46.0% by wt. Dry weight gain 0.0% 13.1% 17.4% 37.8%

EXAMPLE 12

[0085] Three lenses prepared according to Example 7 were each immersedin 2 ml of a deionized water solution of 0.5% w/v, 1.0% w/v and 5.0%w/v, respectively, of dimethylaminoethylmethacrylate+methacrylic acid(DMAEMA:MAA=2:1) in 5 ml glass vials. The lenses were further processedin the same way as described in Example 10.

[0086] Results of certain tests on the untreated lens and the treatedlenses were as follows: DMAEMA + MAA Untreated lens 0.5% 1.0% 5.0% Watercontent, 37.6% 42.5% 45.0% 46.0% by wt. Dry weight gain 0.0% 13.1% 17.4%37.8%

EXAMPLE 13

[0087] A series of contact lenses were cast in polypropylene molds bythermopolymerization of a monomer mixture including methacrylic acid,ethyleneglycol dimethacrylate (EGDMA), initiator and 2-hydroxyethylmethacrylate. The resulting lenses, which had a compositionsubstantially similar to Ocufilicon D had an equilibrium water contentof 48% by weight. Such lenses were utilized for further experiments.

EXAMPLE 14

[0088] A number of contact lenses prepared according to the Example 13were placed to dry to polypropylene baskets. The baskets with lenseswere immersed to a stirred thermostated vessel containing 150 ml of adeionized water solution including 0.35% w/v methacrylic acid, 0.012%w/v EGDMA and 0.05% w/v sodium percarbonate. A vessel lid, furnishedwith a septum, was tightly closed on the vessel, and the vessel waspurged with oxygen free nitrogen for 5 minutes. The lenses wereequilibrated in the solution for 30 minutes at 30° C., then 1.5 ml of 5%w/v Na₂S₂O₅ (sodium metabisulfite) was charged into the vessel toinitiate a redox free radical polymerization. When 30 minutes lapsed, asolution was decanted and replaced with an aqueous solution of 1%NaHCO₆. The lenses were maintained for 30 minutes in the sodiumbicarbonate solution at 50° C. to convert the carboxylic groups into Na+salt. The lenses were then equilibrated in phosphate buffered saline andtheir properties were evaluated.

[0089] The above-noted treatment resulted in slippery, optically clear,mechanically strong, contact lenses with 54% by weight water content.

EXAMPLE 15

[0090] A number of contact lenses prepared according to the Example 13were placed to dry to polypropylene baskets. The baskets with lenseswere immersed to a stirred thermostated vessel containing 150 ml ofdeionized water/20% w/v methanol solution including 0.35% w/vmethacrylic acid and 0.012% w/v EGDMA. The vessel lid, furnished with aseptum, was tightly closed on the vessel. The vessel was purged withoxygen free nitrogen for 5 minutes. The lenses were equilibrated in thesolution for 30 minutes at 45° C., then 0.75 ml of 10% V-50 initiatorwas charged into the vessel. After 45 minutes, the lenses were processedthe same way as in Example 13.

[0091] The treatment resulted in slippery, but slightly turbid,mechanically strong, contact lenses with 56% by weight water content.

EXAMPLE 16

[0092] A number of contact lenses prepared according to the Example 13were placed dry to polypropylene baskets. The baskets with lenses wereimmersed to a stirred thermostated vessel containing 150 ml of adeionized water solution including 0.35% w/v methacrylic acid, 0.012%w/v % EGDMA and 0.28% w/v (sodium persulfate or Na₂S₂O₈). The vessellid, furnished with a septum, was tightly closed on the vessel. Thelenses were equilibrated in the solution for 30 minutes at 30° C., then1.5 ml of 5% w/v (Na₂S₂O₅ or sodium metabisulfite) aqueous solution wascharged into the vessel. After 30 minutes, the lenses were processed insubstantially the same way as in Example 13.

[0093] The treatment resulted in slippery, clear, mechanically strong,contact lenses with 52% by weight water content.

[0094] While this invention has been described with respect to variousspecific examples and embodiments, it is to be understood that theinvention is not limited thereto and that it can be variously practicedwith the scope of the following claims.

What is claimed is:
 1. An ophthalmic lens comprising: a lens bodycomprising a composition including a first crosslinked polymer materialwhich is water swellable; and a second polymeric material, other thanthe first material, selected from the group consisting of water solublepolymeric materials, water swellable polymeric materials and mixturesthereof, the second material being physically immobilized by the firstmaterial.
 2. The ophthalmic lens of claim 1 wherein the lens bodyexhibits at least one of increased water retention, increasedequilibrium water content, increased modulus and reduced surfaceevaporation of water relative to a substantially identical lens bodywithout the second material.
 3. The ophthalmic lens of claim 1 whereinthe lens body has a reduced coefficient of friction relative to asubstantially identical lens body without the second material.
 4. Theophthalmic lens of claim 1 wherein the second material is crosslinked.5. The ophthalmic lens of claim 1 wherein the second material isselected from the group consisting of water soluble polymeric materialand mixtures thereof.
 6. The ophthalmic lens of claim 1 wherein thefirst material is present in an amount in a range of about 10% to about99.9% by weight, based on the water-free weight of the ophthalmic lens;and the second material is present in an amount in a range of about 0.1%to about 90%, by weight, based on the water-free weight of theophthalmic lens.
 7. The ophthalmic lens of claim 1 wherein the firstmaterial is selected from the group consisting of hydrogel-formingpolymers and mixtures thereof.
 8. The ophthalmic lens of claim 1 whereinthe first material includes units derived from at least oneethylenically unsaturated monomeric component.
 9. The ophthalmic lens ofclaim 1 wherein the first material is substantially not covalentlybonded to the crosslinked polymer material.
 10. The ophthalmic lens ofclaim 1 wherein the second material includes units derived from at leastone ethylenically unsaturated monomeric component.
 11. The ophthalmiclens of claim 1 which is in the form of a corneal contact lens.
 12. Amethod for producing an ophthalmic lens comprising: providing a lensbody comprising a lens composition including a first crosslinked polymermaterial which is water swellable; introducing a monomeric componentinto the lens body; and subjecting the monomeric component in the lensbody to effective conditions to form a second polymeric materialselected from the group consisting of water soluble polymeric materials,water swellable polymeric materials and mixtures thereof, the secondmaterial being physically immobilized by the first material.
 13. Themethod of claim 12 wherein the monomeric component is soluble in atleast one member selected from the group consisting of water, watermiscible solvents and mixtures thereof.
 14. The method of claim 12wherein the monomeric component includes an effective amount of acrosslinker.
 15. The method of claim 12 wherein the monomeric componentincludes an amount of a polyfunctional monomer effective to increase themolecular weight of the second material relative to a similar secondmaterial formed without the polyfunctional monomer.
 16. A compositioncomprising: a first crosslinked polymer material which is waterswellable; and a second polymeric material, other than the firstmaterial and polyacrylic acid, selected from the group consisting ofwater soluble polymeric materials, water swellable polymeric materialsand mixtures thereof, the second material being physically immobilizedby the crosslinked polymer material.
 17. The composition of claim 16which has a reduced coefficient of friction relative to a substantiallyidentical composition without the second material.
 18. The compositionof claim 16 wherein the second material is crosslinked.
 19. Thecomposition of claim 16 wherein the second material is selected from thegroup consisting of water soluble polymeric materials and mixturesthereof.
 20. The composition of claim 16 wherein the second material isnonionic, anionic or a material having a substantially balancedcationic/anionic charge.
 21. The composition of claim 16 wherein thefirst material is selected from the group consisting of hydrogel-formingpolymers and mixtures thereof.
 22. The composition of claim 16 whereinthe second material is substantially not covalently bonded to the firstmaterial.
 23. The composition of claim 16 wherein the second materialincludes units derived from at least one ethylenically unsaturatedmonomeric component.
 24. The composition of claim 16 wherein the secondmaterial is selected from the group consisting of water swellablepolymeric materials and mixtures thereof.
 25. A composition comprising:a first crosslinked polymer material which is water swellable; and asecond polymeric material, other than the first material, which isnonionic, cationic or a material having a substantially balancedcationic/anionic charge, and is selected from the group consisting ofwater soluble polymeric materials, water swellable polymeric materialsand mixtures thereof, the second material being physically immobilizedby the first material.
 26. The composition of claim 25 which has areduced coefficient of friction relative to a substantially identicalcomposition without the second material.
 27. The composition of claim 25wherein the second material is crosslinked.
 28. The composition of claim25 wherein the second material is selected from the group consisting ofwater soluble polymeric materials and mixtures thereof.
 29. Thecomposition of claim 25 wherein the first material is selected from thegroup consisting of hydrogel-forming polymers and mixtures thereof. 30.The composition of claim 25 wherein the first material includes unitsderived from at least one ethylenically unsaturated monomeric component.31. The composition of claim 25 wherein the first material is present asa hydrogel in the presence of an effective amount of water to swell thefirst material.
 32. The composition of claim 25 wherein the secondmaterial is substantially not covalently bonded to the crosslinkedpolymer material.
 33. The composition of claim 25 wherein the secondmaterial includes units derived from at least one ethylenicallyunsaturated monomeric component.
 34. The composition of claim 33 whereinthe at least one ethylenically unsaturated monomeric component ispolymerizable to form a linear or branched chain water soluble polymeror copolymer.
 35. The composition of claim 25 wherein the secondmaterial is selected from the group consisting of water swellablepolymeric materials and mixtures thereof.